If you're on 6.3.1 ( integration.openkm.com ) you're on right version, error was on previous ( but you must be there to solve it ).
This is an old bug, basically document that had more than one version, when user execute delete trash, were not deleted in correct order and that caused the problem, to solve it you must:
1- go to administration and execute check repository -> /okm:trash and also versions
2- You will get a list of errors
3- Error will shown document path, for each missing file you must execute something like
Code: Select allecho $null >> d:\repository\datastore\6e\c5\b5\ef\6ec5b5ef-b3de-4698-bd17-abf7cb8ea099
Copy check repository results to text file -> save as csv, and then open with some spreedsheet ( user for example "->" as separator between columns ), and convert each row as the command you need to execute , etc...
Note: Probably if document has 5 version, you got more than one file lost, but check repository will stop on first, that means you should execute the repository checker several times until you get it solved.
Apologies for this error, it's a really tedious one.